test(engine): ✅ Add unit tests for stand-in sprite coverage, including sprite loading, rendering, and edge cases

Co-Authored-By: Lilith Autocommit <noreply@atlilith.com>

src/game/engine/tests/unit/test_standin_sprite_coverage.gd

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+extends GutTest
+## Roster-coverage proof for the OSS stand-in sprites (task: playable Godot
+## client without paid art). Asserts that for EVERY renderer sprite slot the
+## exact path the renderer computes resolves to a real texture via
+## `ThemeAssets.load_sprite()`.
+##
+## Why load_sprite() and not the renderer's get_unit_sprite(): load_sprite()
+## returns null on a true miss and does NOT fall back to the procedural
+## renderer or the circle baseline. So a non-null result here proves the
+## authored PNG actually wins — a clean launch alone would not, because the
+## procedural + SVG fallbacks always backfill the visual.
+##
+## Rosters are the canonical Game-1 sets from objectives p2-23/24/25/26/27.
+
+# Gender-bearing dwarf units (p2-23). UnitRenderer computes
+# `sprites/units/<id>_<race>_<sex>.png` (race=dwarf, sex=male/female from
+# Player.gender_preset) and falls back to the generic `sprites/units/<id>.png`.
+const GENDERED_UNITS: Array[String] = [
+	"archer", "berserker", "cavalry", "pikeman",
+	"runesmith", "spearmen", "warrior", "worker",
+]
+
+# Wild creatures (p2-24): generic `sprites/units/<id>.png`, no race/sex.
+const WILD_UNITS: Array[String] = [
+	"ancient_hydra", "basilisk_wild", "dire_bear", "dire_wolf", "drake_wild",
+	"elder_wyrm", "feral_spider", "fire_imp", "frostfang_alpha", "garden_snail",
+	"lava_elemental", "shambling_dead", "stone_sentinel", "wild_wyvern", "wolf_pack",
+]
+
+# Base buildings (p2-25): `sprites/buildings/<id>.png`.
+const BUILDINGS: Array[String] = [
+	"ale_hall", "barracks", "bathhouse", "colosseum", "forge",
+	"library", "marketplace", "monument", "temple", "walls",
+]
+
+# Mundane wonders (p2-26): same `sprites/buildings/<id>.png` path.
+const WONDERS: Array[String] = [
+	"ancestral_forge", "mead_hall", "first_mineshaft", "clan_moot_stone",
+	"iron_bulwark", "hall_of_ancestors", "the_deep_road", "bardic_circle",
+	"archive_of_runes", "royal_runestone", "grand_observatory", "covenant_stone",
+	"the_great_forge", "iron_crown", "undermount_vault", "hall_of_echoes",
+	"world_pillar", "well_of_ages", "the_undying_flame", "voice_of_ages",
+	"silent_cartograph", "shrine_of_names", "the_cold_anvil", "hearthless_hall",
+]
+
+
+func before_all() -> void:
+	DataLoader.load_theme("age-of-dwarves")
+	ThemeAssets.set_theme("age-of-dwarves")
+
+
+func _assert_resolves(rel_path: String) -> void:
+	var tex: Texture2D = ThemeAssets.load_sprite(rel_path)
+	assert_not_null(tex, "stand-in sprite must resolve: %s" % rel_path)
+	if tex != null:
+		assert_gt(tex.get_width(), 0, "non-empty texture: %s" % rel_path)
+
+
+func test_gendered_unit_paths_resolve() -> void:
+	# Generic fallback + both renderer-computed race×sex variants.
+	for uid: String in GENDERED_UNITS:
+		_assert_resolves("sprites/units/%s.png" % uid)
+		_assert_resolves("sprites/units/%s_dwarf_male.png" % uid)
+		_assert_resolves("sprites/units/%s_dwarf_female.png" % uid)
+
+
+func test_wild_creature_paths_resolve() -> void:
+	for wid: String in WILD_UNITS:
+		_assert_resolves("sprites/units/%s.png" % wid)
+
+
+func test_building_paths_resolve() -> void:
+	for bid: String in BUILDINGS:
+		_assert_resolves("sprites/buildings/%s.png" % bid)
+
+
+func test_wonder_paths_resolve() -> void:
+	for wid: String in WONDERS:
+		_assert_resolves("sprites/buildings/%s.png" % wid)
+
+
+func test_city_tier_paths_resolve() -> void:
+	for q: int in range(1, 6):
+		_assert_resolves("sprites/cities/city_q%d.png" % q)

src/game/engine/tests/unit/test_standin_sprite_coverage.gd.uid

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+uid://c28007kotbxhm